We studied the effects of rapamycin on cultures of erythroid progenitors derived from the peripheral blood of 10 beta-thalassaemia patients differing widely with respect to their potential to produce foetal haemoglobin (HbF). For this, we employed the two-phase liquid culture procedure for growing erythroid progenitors, high performance liquid chromatography for analysis of HbF production and reverse transcription polymerase chain reaction for quantification of the accumulation of globin mRNAs. The results demonstrated that rapamycin induced an increase of HbF in cultures from all the beta-thalassaemia patients studied and an increase of their overall Hb content/cell. The inducing effect of rapamycin was restricted to gamma-globin mRNA accumulation, being only minor for beta-globin and none for alpha-globin mRNAs. The ability of rapamycin to preferentially increase gamma-globin mRNA content and production of HbF in erythroid precursor cells from beta-thalassaemia patients is of great importance as this agent (also known as sirolimus or rapamune) is already in clinical use as an anti-rejection agent following kidney transplantation. These data suggest that rapamycin warrants further evaluation as a potential therapeutic drug in beta-thalassaemia and sickle cell anaemia.

MicroRNAs are a family of small noncoding RNAs regulating gene expression by sequence-selective mRNA targeting, leading to a translational repression or mRNA degradation. The oncomiR miR-221 is highly expressed in human gliomas, as confirmed in this study in samples of low and high grade gliomas, as well in the cell lines U251, U373 and T98G. In order to alter the biological functions of miR-221, a peptide nucleic acid targeting miR-221 (R8-PNA-a221) was produced, bearing a oligoarginine peptide (R8) to facilitate uptake by glioma cells. The effects of R8-PNA-a221 were analyzed in U251, U373 and T98G glioma cells and found to strongly inhibit miR-221. In addition, the effects of R8-PNA-a221 on p27(Kip1) (a target of miR-221) were analyzed in U251 and T98G cells by RT-qPCR and by Western blotting. No change of p27(Kip1) mRNA content occurs in U251 cells in the presence of PNA-a221 (lacking the R8 peptide), whereas significant increase of p27(Kip1) mRNA was observed with the R8-PNA-a221. These data were confirmed by Western blot assay. A clear increment of p27(Kip1) protein expression in the samples treated with R8-PNA-a221 was detected. In addition, R8-PNA-a221 was found able to increase TIMP3 expression (another target of miR-221) in T98G cells. These results suggest that PNAs against oncomiRNA miR-221 might be proposed for experimental treatment of human gliomas.

IL-8 released from bronchial epithelial cells infected with Pseudomonas aeruginosa plays a crucial role in the chronic lung pathology of patients affected by cystic fibrosis. Novel anti-inflammatory approaches will benefit from a thorough understanding of the regulatory mechanisms involved in the transcription of this chemokine to identify potential pharmacological targets. We addressed this issue by investigating the role of phosphoproteins and transcription factors (TFs) on transcription of IL-8 gene in the human bronchial epithelial IB3-1, CuFi-1, and Calu-3 cells. P. aeruginosa increased the basal phosphorylation of the ERK1/2 pathway components 90-kDa ribosomal S6 kinase (RSK)1/2 and mitogen- and stress-activated kinase-2 and of the p38 MAPK pathway components p38α/δ/γ and heat shock protein 27 (HSP27). The involvement of these kinases in the expression of IL-8 gene was confirmed with pharmacological inhibitors of ERK1/2, RSK, p38, and HSP27 both at transcription and secretion levels. Transfection of TF decoy oligodeoxynucleotides, designed to interfere with the interaction of the TFs NF-κB, NF-IL6, AP-1, CREB, and CHOP with the corresponding consensus sequences identified in the IL-8 promoter, reduced the P. aeruginosa-dependent transcription of IL-8, suggesting their participation in the transcriptional machinery. Stimulation of IB3-1 cells with IL-1β led to a similar pattern of activation, whereas the pattern of phosphoproteins and of TFs modulated by TNF-α differentiated sharply. In conclusion, the results highlight a novel role for RSK1/2 and HSP27 phosphoproteins and of the cooperative role of the TFs NF-κB, NF-IL6, AP-1, CHOP, and CREB in P. aeruginosa-dependent induction of transcription of the IL-8 gene in human bronchial epithelial cells.

Herein we describe the activity of a peptide nucleic acid (PNA) that targets microRNA-210 (miR-210), which is associated with hypoxia and is modulated during erythroid differentiation. PNAs directed against miR-210 were designed to bind with high affinity to the target RNA strand and to undergo efficient uptake in target cells. A polyarginine-PNA conjugate directed against miR-210 (Rpep-PNA-a210) showed both very high affinity for RNA and efficient uptake into target cells without the need for transfection reagents. An unmodified PNA of the same sequence displayed the ability to bind RNA, but cellular uptake was very poor. Consistent with this, only Rpep-PNA-a210 strongly inhibited miR-210 activity, as evaluated by assays on undifferentiated K562 cells and on cells treated with mithramycin, which was found to induce erythroid differentiation and miR-210 overexpression. Targeting miR-210 by Rpep-PNA-a210 resulted in: 1) a decrease in miR-210 levels as measured by RT-PCR, 2) up-regulation of raptor mRNA, 3) a decrease in γ-globin mRNA, and 4) decreased expression of differentiated functions (i.e., proportion of benzidine-positive cells, content of embryo-fetal hemoglobins). The efficient delivery of anti-miR PNAs through a suitable peptide carrier (Rpep-PNA-a210) leads to the inhibition of miR-210 activity, altering the expression of miR-210-regulated erythroid functions.

Peptide nucleic acids (PNAs) are very useful tools for gene regulation at different levels, but in particular in the last years their use for targeting microRNA (anti-miR PNAs) has provided impressive advancements. In this respect, microRNAs related to the repression of cystic fibrosis transmembrane conductance regulator (CFTR) gene, which is defective in cystic fibrosis, are of great importance in the development of new type of treatments. In this paper we propose the use of an anti-miR PNA for targeting miR-145, a microRNA reported to suppress CFTR expression. Octaarginine-anti-miR PNA conjugates were delivered to Calu-3 cells, exerting sequence dependent targeting of miR-145-5p. This allowed to enhance expression of the miR-145 regulated CFTR gene, analyzed at mRNA (RT-qPCR, Reverse Transcription quantitative Polymerase Chain Reaction) and CFTR protein (Western blotting) level.